Increased interferon-gamma (IFN-gamma), IL-10 and decreased IL-4 mRNA expression in peripheral blood mononuclear cells (PBMC) from patients with systemic lupus erythematosus (SLE)

Cytokines are important regulators of lymphocyte function in SLE. However, the profile of Th1 and Th2 cytokines produced by circulating lymphocytes in human SLE has not been clearly elucidated. The aim of the present study wa s to characterize the gene expressions of the Th1-type cytokine IFN-gamma, and the Th2-type cytokines IL-10 and IL-4 in PBMC of 15 patients with SLE a nd 10 healthy individuals by a semiquantitative reverse transcriptase polym erase chain reaction (RT-PCR). Our results showed that expression of IFN-ga mma (P = 0.0004) and IL-10 (P = 0.002) transcripts were significantly incre ased in PBMC of patients with SLE compared with healthy controls. By contra st, expression of IL-4 transcripts in PBMC of patients with SLE was signifi cantly decreased compared with the healthy controls (P = 0.0008). Primary s ources of IL-10 were B cells and monocytes, with variable contribution of T cells as detected in various fractions of PBMC of patients with SLE (P = 0 .049). These findings support the hypothesis that the enhanced production o f IFN-gamma by mononuclear cells may trigger inflammatory responses, togeth er with the enhanced production of IL-10 resulting in autoantibody producti on by B cells in human SLE.